Bifunctional Naphtho[2,3-d][1,2,3]triazole-4,9-dione Compounds Exhibit Antitumor Effects In Vitro and In Vivo by Inhibiting Dihydroorotate Dehydrogenase and Inducing Reactive Oxygen Species Production

Abstract

Human dihydroorotate dehydrogenase (hDHODH) is an attractive target for cancer therapy. Based on its crystal structure, we designed and synthesized a focused compound library containing the structural moiety of 1,4-benzoquinone, which possesses reactive oxygen species (ROS) induction capacity. Compound 3s with a naphtho­[2,3-d]­[1,2,3]­triazole-4,9-dione scaffold exhibited inhibitory activity against hDHODH. Further optimization led to compounds 11k and 11l, which inhibited hDHODH activity with IC50 values of 9 and 4.5 nM, respectively. Protein–ligand cocrystal structures clearly depicted hydrogen bond and hydrophobic interactions of 11k and 11l with hDHODH. Compounds 11k and 11l significantly inhibited leukemia cell and solid tumor cell proliferation and induced ROS production, mitochondrial dysfunction, apoptosis, and cell cycle arrest. Nanocrystallization of compound 11l displayed significant in vivo antitumor effects in the Raji xenograft model. Overall, this study provides a novel bifunctional compound 11l with hDHODH inhibition and ROS induction efficacy, which represents a promising anticancer lead worthy of further exploration.

Structural and Thermal Characterization of Halogenated Azidopyridines: Under-Reported Synthons for Medicinal Chemistry

“…Column chromatography was performed with the Teledyne-Isco CombiFlash Rf200 system using pre-packed silica gel column cartridges and hexanes/ethyl acetate or DCM/MeOH as the solvent system. 1 H, 13 C, and 19 F NMR spectra were recorded in CDCl 3 or DMSO-d6 on Bruker Avance 500 or 400 MHz spectrometers. Chemical shifts are reported in ppm with the residual CHCl 3 or DMSO-d5 signal as the reference, and coupling constants (J) are given in Hertz (Hz).…”

“…White crystalline solid. 1 H NMR (500 MHz, CHLOROFORM-d) δ 8.27 (d, J = 5.5 Hz, 1H), 7.14 (d, J = 1.7 Hz, 1H), 6.90 (dd, J = 5.5, 2.0 Hz, 1H); 13…”

“…Light blue solid. 1 General Procedure for the Synthesis of Triazoles (3). To a 4 mL ChemGlass Pressure Relief vial equipped with a magnetic stirbar was added organic azide 2 (1.0 equiv., 0.5 mmol), alkyne 1 (1.1-1.2 equiv., 0.55-0.6 mmol), 1 mL DMF ([reaction] = 0.5 M in DMF), and sparged with N 2 for 5 min while stirring at 23 °C.…”

“…Canary yellow solid. 1 Click reaction between 4-azido-3-bromopyridine 2f (100 mg, 0.50 mmol) and 1.2 equiv. methyl propriolate (51 mg, 0.60 mmol) followed by an aqueous workup with EtOAc (20 mL), water (20 mL), 30% NH 4 OH (aq) (5 mL), and saturated NH 4 Cl (aq) (5 mL) of the product gave 3g (110 mg, 0.38 mmol) in 76% yield.…”

“…Orange solid. 1 To a solution of 6.0 equiv. 2propanol (77 µl, 0.999 mmol) in DMF (951 µl) at 0 °C was added 5.0 equiv.…”